Mediated electrochemical oxidation can be used to convert the organic components of radioactive mixed wastes to CO.sub.2, without risking high-temperature volatilization of radionuclides. Typically, anodic oxidation is used to convert Ag(I) to Ag(II) in HNO.sub.3. Then, Ag(II) reacts with solvent and dissolved organics to produce CO.sub.2. The electrochemical cell used to generate Ag(II), or other mediators, has an electrode separator to prevent deposition of Ag metal on the cathode and the reduction of Ag(II) by the cathode or cathodically-generated species.
There are numerous problems associated with the Ag(I)-Ag(II) process. These problems include: precipitation of Ag(I) by halide anions liberated by the destruction of halogenated organics; diffusion of Ag(I), or other mediators, through the electrode separator, recovery of mediator from the catholyte, generation of NO.sub.x at the cathode, corrosion problems of anode and other cell components in HNO.sub.3 /HCl solutions, leakage of separator seals, separator fouling, and separator rupture.
Accordingly, it is the object of the present invention to provide an electrochemical cell and method which are as simple as possible, but which nevertheless overcome as many of the aforementioned problems as possible.